How to report beginning balance for S-corporation B/S after converting LLC Partnership to S-corporation

In a partnership, "retained earnings" is part of the capital accounts.

I'd report beginning capital account as -120,000.

Keep in mind Scorp's do not have retained earnings, unless they were a Ccorp in past

RE: "On partnership B/S as of 12/31/20 assets is $176K, liabilities is $296K, partner (member) capital account is $149K, retained earnings is $-269K and so equity is $-120K.

In this case how do I report the beginning balance (capitol stock, retained earnings) for S-corporation B/S?"

My take:

The corporation has to take a stance on the stock issuance, and record the common stock info (# of shares, amounts, shareholders etc.)  in its stock register.  I would work with the Board and/or its counsel and, in the tax filing, record the common stock based on the Board's decision as shown by the corporate records.  They may keep all $149K as the common stock.  Or issue stock for a lower or higher amount.  They may ask for me for my feedback.  I would update myself on "adequate capitalization" and related issues and use that as a key element for my advice.  The common stock should be the Board's decision, NOT mine as a tax preparer.  I always advise my corporate clients to maintain and update good corporate records.  The tax filing has to be consistent with such records.  During my career I've seen enough lawsuits to remind me about sticking to this. 

Once the common stock amount is determined, the balance would go to the equity account.

For example, if

1.  the $149K P/S capital was 100% - no more no less - the net (initial plus later capital contributions less distributions) and retained earnings $-269K was truly the net of gains and losses over the years; and 

2.  The board decided to record $100K from the $149K as capital stock and issued shares accordingly.  

I would consider recording Capital Stock $100K; Paid in capital $49K and R/E -269K.

If those two numbers were commingled (with draw, losses...) over the years, you're on your own.

For an S corp, two other key tax reporting items include (1) the AAA account, which would start with zero for the year of conversion, and (2) the stock basis and debt basis. 

Did the liabilities include any loans or advances from the partners (thus shareholders)?  If NOT, it could create an tax issue in that the stock may start with a negative basis and because any further loss without injection of capital or loans from shareholders may have deductibility issues.  The at risk rules for partnerships and S corporations are different.